The invention relates to a pipe cutting apparatus. DE-B 1 171 241 discloses a cutting apparatus having a fixed, concentrically acting work-holding fixture. This pipe cutting apparatus has a rotary body which can be rotated manually around the workpiece and has a cutting head carrying the disc-shaped, motor-driven cutting tool. During the pivoting movement of the rotary body, the cutting head is radially controlled by a lead cam arranged concentrically to the pipe axis.
Other, pipe cutting apparatuses are known in which the cutting device is guided about the pipe to be cut by means of a drive.
The safety aspects are a disadvantage of the known pipe cutting apparatuses. In particular in the case of large pipe diameters, with regard to both the pipe diameter and the wall thickness, larger drives and tools, which make the apparatus heavier, are required. For ergonomic reasons, manual actuation may therefore lead more easily to accidents or to damage to the tools and machines. Furthermore, it may be a disadvantage that the pipe cutting apparatus swings out in an uncontrolled manner in both directions.
Accordingly, it is a principle object of the invention to provide a pipe cutting apparatus which is safer than the prior art and wherein the actual operation for cutting the pipe can be carried out safely in a controllable manner.
The foregoing object is achieved by providing a pipe cutting apparatus having a transmission gearing which has a spur gear interacting with a crown gear. The use of a transmission ratio from the spur gear with the crown gear which is arranged on the rotary body travelling around the pipe to be cut results in a simple and compact solution to the abovementioned problems in terms of design.
In a preferred embodiment, a free-wheel mechanism is connected upstream of the spur gear. The free-wheel mechanism prevents an incorrect feed direction. It is only possible to work in the desired direction of the tool. The desired safety is achieved with this solution variant.
Worm gearing is advantageously connected upstream of the spur gear. The worm gearing offers an operationally safe locking function, in which case, for example, a manual movement of the drive and thus of the tool in an incorrect direction is prevented.
The processing operation can be effected via an actuating device, on the one hand, and mechanically via a drive motor, on the other hand, in which case the actuating device may be a crank handle, suitably arranged on the transmission gearing, or a handwheel.
The transmission gearing is preferably connected to the work-holding fixture in a fixed manner at the bearing holder for the rotary body mounted therein.
In addition, the transmission gearing can be connected in position in a pivotable or rotatable manner with respect to the work-holding fixture. Depending on spatial conditions, it is advantageous if the transmission gearing and thus the manual or mechanical drive are possible from various directions. To this end, an alternative possibility is for the transmission gearing to be provided with the actuating devices in such a way that it can be pivoted and then locked with respect to the bearing holder.
The drive of the transmission gearing is advantageously effected by means of a flexible shaft.
It is conceivable for the drive of the transmission gearing, instead of being directly coupled to the transmission gearing, to be attached to the workbench or to the fixed bearing holder, etc. In this case, the drive could be coupled to the transmission gearing via a flexible shaft, for example, or in another similar manner.